Over the years I have heard of Aikidoka being paralyzed or killed while taking ukemi for particular techniques. The main one involved is Shihonage because if Nage jerks down very hard as Uke moves forward, Uke can flip up and come down on their neck.

I have never understood this type of training and most likely never will. In class it is Nage's RESPONSIBILITY to take care of Uke. Such behavior on the part of Nage is criminal, not to mention poor training.

In regards the situation where the woman died as a result of too many breakfalls in a short period of time, where was her instructor? Was the instructor qualified to be teaching? Given that the instructor had a student die under their tutelage, I would presume that the instructor really is not fit to be trusted with students.

Too many breakfalls over a period without sufficient rest and recovery and water, can lead to a bruising of the kidneys. Ultimatley, this bruising can lead to kidney failure.

"Train hard" does not mean "train hard and stupid".

For me it is always "why" the student is training that determines "how" they train. Instructors also should be clear on their "why" they are teaching and "how" they are teaching. They should be clear to all of their students on both of these.